#include <bits/stdc++.h>
using namespace std;
#define fileio() freopen("input.txt","r",stdin); freopen("output.txt","w",stdout)
#define fio() ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define all(x) (x).begin(), (x).end()
#define allr(x) x.rbegin(), x.rend()
#define cmprs(x) sort(all(x)),x.erase(unique(all(x)),x.end())
#define endl "\n"
#define sp " "
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define F first
#define S second
#define rz resize
#define sz(a) (int)(a.size())
#define clr(a) a.clear()
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, ll> pil;
typedef tuple<int, int, int> tpi;
typedef tuple<ll, ll, ll> tpl;
typedef pair<double, ll> pdl;
typedef pair<double, int> pdi;
const int dx[] = {1,-1,0,0,1,1,-1,-1};
const int dy[] = {0,0,1,-1,1,-1,1,-1};
const ll MOD = 1e9+7;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3f;
const int MAX = 101010; // PLZ CHK!
inline pll sum(pll a, pll b) {return {a.first+b.first,a.second+b.second};}
struct hld {
struct segtr{
//0-indexed!
vector<pll> tr; int n;
void rst(int sz) {
n=sz;
tr.resize((n+1)<<1,{0,0});
}
void upd(int i, ll v) {
tr[i+n]=sum(tr[i+n],pll{v,1}); i+=n; //AWARE OF UPD POLICY!!
for (i>>=1; i; i>>=1) tr[i]=sum(tr[i<<1],tr[i<<1|1]);
}
pll qry(int l, int r) {
pll ret={0,0};
for (l+=n, r+=n; l<=r; l>>=1, r>>=1) {
if (l&1) ret=sum(ret,tr[l++]);
if (~r&1) ret=sum(ret,tr[r--]);
}
return ret;
}
};
int n,pv=0;
vector<int> sz,dep,par,in,out,top;
segtr seg;
vector<vector<int>> g0,g;
void init(int _n) {
n=_n+10;
sz.resize(n),dep.resize(n),par.resize(n),top.resize(n),
in.resize(n),out.resize(n),g0.resize(n),g.resize(n);
seg.rst(n);
}
void dfs0(int cur=1, int prv=-1) {
for (int nxt:g0[cur]) {
if (nxt==prv) continue;
g[cur].pb(nxt);
dfs0(nxt,cur);
}
}
void dfs1(int cur=1) {
sz[cur]=1;
for (int &nxt:g[cur]) {
par[nxt]=cur;
dep[nxt]=dep[cur]+1;
dfs1(nxt);
sz[cur]+=sz[nxt];
if (sz[nxt]>sz[g[cur][0]]) swap(nxt,g[cur][0]);
}
}
void dfs2(int cur=1) {
in[cur]=++pv;
for (int nxt:g[cur]) {
top[nxt]=(nxt==g[cur][0]?top[cur]:nxt);
dfs2(nxt);
}
out[cur]=pv;
}
pll qry(int a, int b) {
pll ret={0,0};
while (top[a]!=top[b]) {
if (dep[top[a]]<dep[top[b]]) swap(a,b);
ret=sum(ret,seg.qry(in[top[a]],in[a]));
a=par[top[a]];
}
if (dep[a]>dep[b]) swap(a,b);
ret=sum(ret,seg.qry(in[a]+1,in[b]));
return ret;
}
void upd(int a, int b, ll v) {
if (dep[a]<dep[b]) swap(a,b);
seg.upd(in[a],v);
}
};
typedef array<ll,4> arr;
int N,M,T;
pii E[MAX];
pll C[MAX];
arr Q[MAX];
int L[MAX],R[MAX],ans[MAX];
int main() {
fio();
cin>>N>>M>>T;
for (int i=0; i<N-1; i++) {
int u,v; cin>>u>>v;
E[i]={u,v};
}
for (int i=0; i<M; i++) {
int p,c; cin>>p>>c;
C[i]={c,p-1};
}
for (int i=0; i<T; i++) {
ll s,t,x,y; cin>>s>>t>>x>>y;
Q[i]={s,t,x,y};
}
sort(C,C+M);
fill(ans,ans+MAX,0);
fill(L,L+MAX,0);
fill(R,R+MAX,M-1);
while (1) {
bool flg=0;
vector<int> mid[M+10];
for (int i=0; i<T; i++) {
if (L[i]<=R[i]) {
flg=1;
mid[L[i]+R[i]>>1].pb(i);
}
}
if (!flg) break;
hld h; h.init(N);
for (int i=0; i<N-1; i++) {
auto [u,v]=E[i];
h.g0[u].pb(v), h.g0[v].pb(u);
}
h.dfs0(), h.dfs1(), h.dfs2();
for (int i=0; i<M; i++) {
auto [cst,edg]=C[i];
auto [u,v]=E[edg];
h.upd(u,v,cst);
for (int idx:mid[i]) {
auto [s,t,x,y]=Q[idx];
auto [sil,cnt]=h.qry(s,t);
// if (idx==0) cout<<sil<<sp<<cnt<<sp<<y<<endl;
if (sil<=y) {
ans[idx]=max(ans[idx],(int)cnt);
L[idx]=i+1;
}
else R[idx]=i-1;
}
}
}
// cout<<endl;
hld h; h.init(N);
for (int i=0; i<N-1; i++) {
auto [u,v]=E[i];
h.g0[u].pb(v), h.g0[v].pb(u);
}
h.dfs0(), h.dfs1(), h.dfs2();
for (int i=0; i<M; i++) {
auto [cst,edg]=C[i];
auto [u,v]=E[edg];
h.upd(u,v,cst);
}
for (int i=0; i<T; i++) {
auto [s,t,x,y]=Q[i];
auto [sil,cnt]=h.qry(s,t);
// cout<<s<<sp<<t<<sp<<cnt<<sp<<ans[i]<<endl;
cout<<max(-1ll,x-(cnt-ans[i]))<<endl;
}
return 0;
}
